Mechanical and durability properties of concrete mixed and cured in hypersaline water

Abstract

Abstract This study investigates the influence of hypersaline water on the compressive strength, bleeding, and water absorption of concrete, comparing freshwater and saltwater curing environments. Mixes were prepared using 0%, 10%, 15%, 20%, and 30% saltwater by weight of mixing water (0, 100, 150, 200, and 300 g/L of dissolved salt), with water-cement ratio of 0.5 and mix ratio of 1:1.62:4.38 (cement: fine: coarse). Concrete cubes were cured for 7, 14, and 28 days in freshwater or corresponding saline environments. Results showed compressive strength deterioration with increasing salinity. For freshwater-cured samples, 28-day strength declined from 28.27 MPa (0%) to 14.01 MPa (30%), a 50% loss. Saltwater curing caused greater reductions, from 28.27 MPa to 10.33 MPa (30% SW), nearly 64% loss. Freshwater mixes exposed to saline curing exhibited partial recovery (e.g., 0% in 15% SW reached 17.29 MPa at 28 days), possibly linked to early hydration effects on chloride interference. Water absorption increased with salinity in freshwater-cured specimens, from 1.97% to 3.54%, while saltwater-cured concretes showed variable absorption, with a slight reduction at 30% SW (1.91%). Regression between compressive strength and water absorption using MATLAB R2025b showed inverse but environment-dependent trends (R 2 = 0.706 for freshwater, R 2 = 0.885 for saltwater; combined R 2 = 0.076). Bleeding rate also increased with salinity, from 4.76% to 6.44%, indicating interference with cement-water cohesion. Overall, hypersaline mixing and curing significantly slowed strength development while increasing water absorption and bleeding, highlighting the critical influence of saline environments on concrete durability under severe laboratory exposure conditions.